1. Field of the Invention
The present invention relates generally to methods and apparatus for operating well bore tubing and, more particularly, to advancing the bottom assembly of a drilling string and/or freeing the drilling string including but not limited to a coiled tubing string in a borehole.
2. Description of the Prior Related Art
It is well known to those of skill in the art that there are limits to the ability of a surface rig to push a tubular string into a bore hole. After a certain depth is reached, the flexibility of the tubular string does not permit the transmission of force through the length of the string to move the bottom hole assembly. An analogy often made is that of attempting to push a string through a long or sticky tube.
The problem occurs in the drilling of oil and gas wells due to the length of the tubular strings and the drag and potential sticking of the drill string against the well bore wall. This results in increased resistance to movement of the pipe.
This effect is often more evident in a coiled tubing applications. Coiled tubing is typically even more flexible than drill pipes. Coiled tubing strings cannot be rotated in the well bore like drill strings. Coiled tubing also to some extent retains the spiral effect of the diameter of the reel on which the coiled tubing is stored. Therefore, coil tubing may have additional points of drag and sticking of the coiled tubing in the well bore as compared with standard drilling pipe even though the effect is also present with standard drilling pipe.
In wells with high angles and/or horizontal sections, this problem becomes greatly exaggerated, often essentially prohibiting advancement of the drill string.
Many attempts and methods have been employed in the past by those of skill in the art to solve this problem. Prior art attempts to solve problems have included downhole tractors, jars, centralizers, and even wheels and skids. Other attempts utilize pulsation inducing devices, which lengthens the pipe momentarily by a small amount by restricting flow through the drill pipe. However, this technique results in increased fatigue of the drill string. As well, the on and off fluid pulses may not operate downhole motors effectively.
In some cases, the pipe string becomes stuck in the well bore so the string can neither be moved up or down. Perhaps even more devices and methods have been provided to simply loosen and retrieve the stuck string rather than attempting to go deeper in the well. Accordingly, these devices are not designed for advancing the drill string further into the well but rather attempt to retrieve the stuck drill pipe or at least a portion thereof.
The following patents discuss various attempts related to the above discussed problems.
U.S. Pat. No. 3,152,642, issued Oct. 13, 1964, to A. G. Bodine discloses a method of loosening an elastic column (drill string), which is stuck in a well at a distance down from the upper end and which is acoustically free there above that includes applying a torsional bias to the column, acoustically coupling the vibratory output member of a freely operating torsional elastic wave generator to the acoustically free portion of the column above the stuck point and in a manner to apply an alternating torque to the column, and operating the generator at a torsional resonant frequency of the column, and at a power output level developing a cyclic force at the stuck point which exceeds and opposes the force holding the column at the stuck point.
U.S. Pat. No. 3,155,163, issued Nov. 3, 1964, to A. G. Bodine discloses an apparatus for loosening a fish (drill string) at a point below its upper end in a bore hole, includes a grappling tool adapted to rigidly engage the upper end of the fish, a drill collar coupled to the grappling tool, an acoustic vibration located adjacent the upper end of the drill collar comprising a mass element rotatable on and linearly reciprocal along the vertical axis of the drill collar, a non-rotatable member adapted for corresponding reciprocation along the axis, cam means between the mass element and the non-rotatable member for converting rotation of said mass element into axial vibration of the mass element the non-rotatable members, the non-rotatable reciprocal member being coupled to the drill collar for transmission of reciprocating force to the upper end thereof to set up in the collar and fish an acoustic standing wave, an inertia collar adapted to be lowered into the bore hole on a rotatable drill pipe string, suspended from a rotary table at the ground surface, and a torque transmitting spring connecting said inertial collar and the rotatable mass element of the wave generator, the spring being yieldable in a vertical direction too isolate the inertia collar from vibration transmitted upwards from the wave generator.
U.S. Pat. No. 3,500,908, issued Mar. 17, 1970, to D. S. Barler discloses a device for freeing a tubular member stuck within an oil well comprising upper and lower frames mounted on the surface, horizontal plates, a plurality of cylindrical shells, a plurality of pistons mounted in the shells, a plurality of helical springs, means for adjustably supporting the frame at a desired elevation above the well, a pair of heavy eccentrically loaded, power driven bodies that are transversely spaced a fixed distance in a horizontal plane and rotate in opposite directions, with the eccentric loading, and rigid frame members to support the power driven bodies.
U.S. Pat. No. 3,168,140, to A. G. Bodine, issued Feb. 2, 1965, discloses a method of moving a column system embodying a portion held fast in the earth and a portion extending therefrom which is acoustically free and in a condition to sustain a vibration wave pattern that comprises acoustically coupling a fluid-drive vibrator to the acoustically free portion of the column system at a point spaced from and the held portion, and fluid driving the vibration at a frequency which produces resonance of the column system and which establishes a vibration patter with cyclic impulse force in the column system with the region of the held portion, where in the resonant frequency and the vibration patter are established independently of minor irregularities in fluid drive effort by reason of inherent fluid drive flexibility.
U.S. Pat. No. 4,429,743, to Bodine, issued Feb. 7, 1984, discloses a well servicing system in which sonic energy is transmitted down a pipe string to a down hole work area a substantial distance below the surface. The sonic energy is generated by an orbiting mass oscillator and coupled therefrom to a central stem to which the piston of a cylinder-piston assembly is connected. The cylinder is suspended from a suitable suspension means such as a derrick, with the pipe string being suspended from the cylinder in an in-line relationship therewith. The fluid in the cylinder affords compliant loading for the piston while the fluid provides sufficiently high pressure to handle the load of the pipe string and any pulling force thereon. The sonic energy is coupled to the pipe string in a longitudinal vibration mode which tends to maintain this energy along the string.
U.S. Pat. No. 4,667,742, to Bodine, issued May 26, 1987, discloses a method wherein the location of a section of drill pipe which has become stuck in a well some distance from the surface is first determined. The drill string above this location is unfastened from the drill string and removed from the well. A mechanical oscillator is connected to the bottom of the re-installed drill string through a sonic isolator section of drill pipe designed to minimize transfer of sonic energy to the sections of drill string above the oscillator. The oscillator is connected to the down hole stuck drill pipe section for transferring sonic energy thereto. A mud turbine is connected to the oscillator, this turbine being rotatably driven by a mud stream fed from the surface. The turbine rotates the oscillator to generate sonic energy typically in a torsional or quadrature mode of oscillation, this sonic energy being transferred to the stuck section of drill pipe to effect its freeing from the walls of the well.
The above discussed prior art does not address solutions provided by the present invention, which teaches a system that is useful for both advancing the bottom hole assembly further into the well and/or for loosening the pipe to prevent or to free the pipe from becoming stuck in the well bore. The prior art also does not show a tool which has the ability to be reversed causing the drill string to be moved back up the hole.
Consequently, those skilled in the art will appreciate the present invention that addresses the above described and other problems.